ML24341A035
| ML24341A035 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 12/30/2024 |
| From: | Amy Snyder Reactor Decommissioning Branch |
| To: | Shaun Anderson Reactor Decommissioning Branch |
| References | |
| Download: ML24341A035 (1) | |
Text
MEMORANDUM TO:
Shaun Anderson, Branch Chief Reactor Decommissioning Branch Division of Decommissioning, Uranium Recovery and Waste Programs Office of Nuclear Material Safety and Safeguards FROM:
Amy Snyder, Senior Project Manager Reactor Decommissioning Branch Division of Decommissioning, Uranium Recovery and Waste Programs Office of Nuclear Material Safety and Safeguards
SUBJECT:
LICENSE TERMINATION PLAN LICENSE APPLICATION REQUEST -CLARIFICATION CALL ON REQUEST FOR SUPPLEMENTAL INFORMATION MEETING
SUMMARY
On October 4, 2024 (Agencywide Documents and Management System (ADAMS) Accession No. ML24269A043 Pkg), the U.S. Nuclear Regulatory Commission (NRC) issued a request for supplemental information (RSI) as related to the acceptance review of the Holtec Decommissioning International, LLC (HDI) Oyster Creek Nuclear Generating Station License Termination Plan License Application Request (LAR) (ML24214A037). On October 10, 2024, the NRC issued (ML24284A174) the RSI and Pending Request for Additional Information due to discovery of a version control issue. On October 23 and October 29, 2024, the NRC held clarification calls with HDI on RSI 1-9. RSIs 1-7 were discussed on October 23 and RSIs 8 and 9 were discussed on October 29. A summary of the HDIs RSI comments and questions and the staffs clarification responses and comments are documented in the enclosure 1. A list of attendees is documented in enclosure 2. The NRC staff made no decisions at this meeting. The NRC staff will evaluate the HDI RSI responses upon submittal.
In accordance with 10 CFR 2.390, a copy of this letter will be available electronically for public inspection in the NRC Public Document Room or from the Publicly Available Records component of NRCs ADAMS. ADAMS is accessible from the NRC Website at http://www.nrc.gov/reading-rm/adams.html.
Docket Nos.: 50-219 and 72-15 License No.: DPR-16
Enclosures:
- 1. Clarification Questions and Comments
- 2. List of Attendees CONTACT: Amy Snyder, NMSS/DUWP 301-415-6822 December 30, 2024 Doell, Marlayna signing on behalf of Snyder, Amy on 12/30/24
SUBJECT:
LICENSE TERMINATION PLAN LICENSE APPLICATION REQUEST -
CLARIFICATION CALL ON REQUEST FOR SUPPLEMENTAL INFORMATION MEETING
SUMMARY
DATE December 30, 2024 DISTRIBUTION:
Public JWhitman, NMSS/DUWP CMcKenney, NMSS/DUWP SAnderson, NMSS/DUWP ASnyder, NMSS/DUWP CBarr, NMSS/DWUP RFedors, NMSS/DUWP KLois, NMSS/REFS KRobertson-DeMers, NMSS/DUWP MDoell, NMSS/DUWP ADAMS Accession Number: ML24341A035 OFFICE DUWP DUWP DUWP DUWP NAME A. Snyder S. Anderson C. McKenney A. Snyder DATE 12/06/2024 12/27/2024 12/27/2024 12/30/2024 OFFICIAL RECORD COPY
ENCLOSURE 1 OYSTER CREEK NUCLEAR GENERATING STATION (OCNGS)
REQUEST FOR SUPPLEMENTAL INFORMATION (RSI) - ACCEPTANCE REVIEW FOR THE LICENSE TERMINATION PLAN LICENSE APPLICATION REQUEST CLARIFICATION CALL MEETING
SUMMARY
Item No.
RSI LICENSEE QUESTION AND STAFF RESPONSE RSI-1 Identify and describe the survey units within each area of the site, including the classification, area, and general information on surrounding survey units. Include maps with defined boundaries of the survey units, the scan and sample locations, and survey unit sizes.
Holtec Decommissioning International-OCNGS (HDI)
Questions/Comments: HDI asked what the staff means by identifying surveys units at this stage of the decommissioning because more characterization will be conducted.
Staffs Comments: Because HDI committed to follow Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM) (NUREG-1575), the NRC staff will accept, at minimum, the classification of the designated areas on site. However, if a licensee wants to go beyond the size limitation in MARSSIM, the staff expects justification in the form of what method or criteria the licensee plans on using in the License Termination Plan (LTP) License Application Request (LAR).
The NRC staff explained that a licensee can identify in its LTP LAR a section that specifies what a licensee can change without NRC approval (without the need for an amendment). One of the items in this section of the LTP typically identify the changes a licensee can make to survey unit classification on its own. A licensee can change a survey unit classification up but not down without NRC approval. Without identification of survey area classes, such a criterion would not be able to be implemented.
Further, the NRC staff stated that a licensee should identify survey unit areas and explain whether there will be overlaps in individual survey unit. This is important to calculation of final status survey (FSS) dose for each survey unit is considered a compliance unit. Groundwater concentration in the highest area must be included in one FSS unit for compliance demonstration purposes.
Item No.
RSI LICENSEE QUESTION AND STAFF RESPONSE RSI-2 Site Characterization: Provide the radionuclide fractions, including characterization data used to derive them, to evaluate radionuclides of concern (ROCs), insignificant contributors, surrogate ratios, relative ratios, and instrument efficiency.
HDI Questions/Comments: Does HDI have to measure all radionuclides? HDI explains that it plans to characterize throughout decommissioning and have a radionuclide profile for each building as it gets closer to FSS. HDI stated it believes that the profile will change as the remediation progresses. HDI plans on developing radionuclide fractions after the LTP is approved. Co-60 and Cs-137 are strong gammas and will be used to represent all radionuclides.
Staffs Comments: The License Termination Plan is about the end state and should have radionuclide initial fractions. This information is needed to evaluate the characterization summary which is required to be submitted as part of the LTP LAR or the licensee should provide justification of why such data are not necessary. Without such information, the NRC staff will not be able to approve the clean-up criteria and would have no understanding what is there, how a licensee would measure it, and account for certain radionuclides for decision-making1.
Further, all radionuclides of concern are not strong gamma emitters.
Therefore, in a proposal like this, a licensee should justify whether other ROCs that are not strong gamma emitters would behave the same way in the environment and therefore be present alongside of Co-60 and Cs-137.
1 Refer to related NRC staff comments in RSI-7.
Item No.
RSI LICENSEE QUESTION AND STAFF RESPONSE RSI-3, Oyster Creek Generating Station Site Radiological Characterization Report: For the samples selected for Hard-to-Detect (HTD) analysis, include the full suite of radionuclides in Table 2-7, Radionuclides of Concern (ROC), or provide justification for why a full suite of radionuclides was not provided.
HDI Questions/Comments: Does HDI have to provide a full suite for all samples? HDI explained the initial approach of analyzing for the full suite of ROCs was replaced with the use of indicator radionuclides. When indicator radionuclides do not show significant activity, analysis for the full suite of radionuclides was not considered necessary. HDI noted that Pu-241 was the most prevalent plutonium species and suitable as an indicator for alpha emitters.
Staffs Comments: NRC staff pointed out the licensees LTP commits to analyzing 10% of all soil samples for the full suite of radionuclides.
However, sample results in the LTP and characterization reports only include a portion of the ROCs. The NRC staff indicated that for gamma emitters (other than Cs-137 and Co-60) data should be available in the laboratory gamma spectroscopy reports. Given this data already exists, HDI may include these values in its data summaries. NRC staff indicated that it appears that the licensee had not made a sufficient case for eliminating the analysis of all alpha emitters in the absence Pu-241 and/or Am-241. Analyzing a subset of samples for the full suite of radionuclides supports the development of radionuclide fractions. No decision will be made until the HDI submits it response and the staff evaluates it.
Item No.
RSI LICENSEE QUESTION AND STAFF RESPONSE RSI-4, Oyster Creek Generating Station Site Radiological Characterization Report: Justify the selection of surface soil samples without easy to-detect (ETD) activity for HTD analysis, as these samples would not be expected to contain HTD radionuclides.
HDI Questions/Comments: The HDI indicated that it understood the concern regarding selection of surface soil samples without detectable ETD for HTD analysis. HDI indicated that the samples listed in the RSI were collected from the Radiologically Controlled Area (RCA), Class 1 area, which was expected to undergo remediation. HDI indicated that given the remediation planned, the current HTD analysis may not yield meaningful results for post-remediation conditions. Post-remediation, HDI stated it will reassess the need for detailed HTD analysis as part of the FSS planning process.
Staffs Comments: Samples without positive ETD concentrations would not be expected to contain HTDs. Generally, samples with the highest concentration of ETDs are selected for HTD analysis. NRC staff indicated that samples provided in the LTP LAR appear to be examples of samples with significant ETD activity that were not selected for HTD analysis. Staff did not make any conclusions. Staff will evaluate the RSI responses when submitted and then make a determination.
Item No.
RSI LICENSEE QUESTION AND STAFF RESPONSE RSI-5, Oyster Creek Generating Station Site Radiological Characterization Report: Evaluate other contaminated media (e.g.,
pavement-covered areas and shallow concrete slabs, sediment, subsurface soils) for the full suite of radionuclides to establish radionuclide fractions and subsequent determination of insignificant contributors, surrogate ratios, and relative ratios.
HDI Questions/Comments: HDI indicated that continuing characterization would be implemented in a phased approach. Soil beneath removed asphalt and pavement-covered areas, and subsurface soils will be re-evaluated post-demolition to support the assessment of radionuclide fractions, surrogate ratios, and insignificant contributors, where applicable. HDI clarified that the asphalt and concrete slabs would be removed to expose the underlying soil for walk-over surveys and measurements. HDI stated that an HTD analysis for these media is not needed. HDI indicated the sediment samples listed in RSI-4 were collected from above the asphalt in areas where spills occurred.
Also, HDI stated that it recognizes there are areas with increasing contamination at the depth; however, it plans to remediate subsurface soil containing residual radioactivity. There will be further characterization following these activities. HDI indicated that it plans to conduct characterization of piping, additional sediment sampling in the Discharge Canal Area (DCA), and a trenching campaign in the North Yard.
Staffs Comments:
The NRC staff stated that licensees should provide a clear initial list of what they believe will remain at the end state, if they chose to follow MARSSIM and will later update their information. The NRC staff has traditionally accepted licensee provided conservative lists in their LTPs that they later confirm.
NRC staff clarified that the RSI was asked because licensees analysis of a subset of subsurface soils and other media for the full suite of radionuclides to develop radionuclide fractions for these media often show fractions that differ from surface soils.
Item No.
RSI LICENSEE QUESTION AND STAFF RESPONSE RSI-6, Oyster Creek Nuclear Generating Station Below Grade Structures Radiological Characterization Report: Provide measured activity, uncertainty, and the MDC (Minimum Dectectable Concentration) for all radionuclide analyses conducted on each sample, including those with results less than the MDC to support the staffs review of the radionuclide fractions, insignificant contributors, surrogate ratios, and relative ratios.
HDI Comments/Questions: HDI agreed to provide a table of initial ETD and HTD sample results.
Staffs Comments:
The NRC staff understood HDIs proposed action and looks forward to reviewing the information.
Item No.
RSI LICENSEE QUESTION AND STAFF RESPONSE RSI-7 OC LTP & Enclosure 6, Oyster Creek Nuclear Generating Station Below Grade Structures Radiological Characterization Report: Samples selected for HTD analysis should include the full suite of radionuclides in Table 2-7.
HDI Comments/Questions: HDI explained that it applied a logic tree using indicator radionuclides to determine which samples underwent what radionuclide analysis. Thus, not all samples were analyzed for the full suite of radionuclides. HDI plans to provide additional data in the future with a broader HTD analysis where appropriate. HDI explained that a reassessment of radionuclide fractions, surrogate ratios, and insignificant contributors will be conducted post-remediation during the FSS phase.
Staffs Comments: The NRC staff encourages licensees to review existing data to determine if sufficient information is available to develop initial radionuclide fractions. NRC staff explained when some important information is not available at the time of the LTP submission, bounding assumptions are reasonable. The NRC staff will consider assumptions to be commitments to ensure subsequent demonstrations remain true.
The NRC staff noted that if the information is not available, it would have to determine if the new approach would be viable and acceptable for staff review. A license condition may be needed or could be acceptable if it does not push an evaluation needed for LTP approval into the future. If it pushes an evaluation into the future, an amendment would be needed.
Depending on the circumstances and the type of information that is not specifically included in the LTP,2, the NRC staff may consider requiring license conditions to formalize the licensees commitments. This may be accomplished by a specific license condition or by reference to the approved LTP (i.e., in the tie-down condition).
2 For example, if a specific methodology is not identified in the LTP, a licensee can commit to the specific methodology in MARSSIM or some other method that the staff finds acceptable for determining the specific number of samples needed for FSS for a survey unit. Licensees should contact the NRC staff for the details on implementing these types of licensee commitments.
Item No.
RSI LICENSEE QUESTION AND STAFF RESPONSE RSI-8*
Insignificant Contributors: Provide representative (additional) RCA sample data by area and media to support the determination of radionuclide fractions and the subsequent evaluation of insignificant contributors based on this data.
Explain what further investigations were or will be conducted to determine the horizontal and vertical extent of the Sr-90 contamination in the RCA.
HDI Questions/Comments: HDI will be collecting data from areas in the future that are now inaccessible.
Staffs Comments:
In general, the NRC staff indicated that post-remediation data may be difficult for determining radionuclide fractions as they are not expected to contain sufficient concentrations of residual radioactivity. The highest concentrations of the radionuclides relative to pre-remediation samples may be quite different that may warrant reworking several key values such as instrument sensitivity. On the other hand, if a licensee chooses to use bounding scenarios for radionuclide fractions, samples should be taken during subsequent surveys to verify these radionuclide fractions remain bounding. If not bounding rework may be needed.
The NRC staff noted if a license does not know enough about the site characteristics and has not described its specific methodologies in detail, it may be premature to submit a LTP LAR. The NRC staff noted that it appears that the HDI strategy is to provide identification of radionuclide fractions, surrogate radionuclides, and instrument sensitivities for each area of the site and building after remediation and all characterization is completed. With such a strategy provided by a licensee, without more details, a license amendment may be needed later, should the NRC accept the LTP LAR for detailed technical review. The NRC staff did not draw any conclusions or make any decisions. It will do so upon review of the HDI submittal of the RSI response.
HDI stated that it has not settled on a strategy. The staff asked HDI if it believes it is on track to meet the March 31, 2024, RSI response date or if it needs more time? HDI responded that it believes currently that it will be able to meet the March 31, 2024, date.
Item No.
RSI LICENSEE QUESTION AND STAFF RESPONSE RSI-9*
Provide the Less Likely But Plausible (LLBP) exposure scenarios results discussed in the OCNGS LTP to provide information to the NRC staff to risk inform the compliance decision.
HDI Comments/Questions: HDI identified the LLBP exposures scenarios in the LTP LAR as the Resident, Resident Farmer, and the Recreational Scenarios. HDI chose the Industrial Scenario for the compliance scenario. HDI inquired about guidance on what types of scenarios should be considered including alternative scenarios?
Staffs Comments:
NRC staff are seeking the results of the dose estimates for less likely but plausible exposure scenarios to ensure that the consequences of leaving behind residual radioactivity would not lead to unacceptably high risk considering both the likelihood and magnitude of the potential dose.
Licensee may refer to NUREG-1757, Volume 2, Revision 2, Consolidated Decommissioning Guidance, Characterization, Survey, and Determination of Radiological Criteria (ML22194A859), Table 5.1 for guidance on the various types of exposure scenarios that should be considered including plausible exposure scenarios which should be assessed to determine potential risk and implausible scenarios which do not have to assessed due to the low likelihood of those scenarios. This guidance is one way the NRC has found acceptable. According to this guidance, alternative scenarios are typically considered less likely but plausible exposure scenarios that due to their relatively low likelihood do not have to strictly meet the dose criteria in 10 CFR Part 20, Standards for Protection Against Radiation, Subpart E, Radiological Criteria for License Termination.
In addition, if the licensee decides to use the guidance referenced above, the NRC staff explained that a licensee may present arguments on why the residential scenarios bound the potential risk from the recreational scenario, or why the residential farmer scenario is very low likelihood or implausible while the residential gardener is LLBP.
- RSI-8 and 9 were discussed on 10/29/24. Other RSIs were discussed on 10/23/24.
ENCLOSURE 2 LIST OF ATTENDEES AT THE OCTOBER AND NOVEMBER 2024, CLARIFICATION CALL ON THE OYSTER CREEK NUCLEAR GENERATING STATION (OCNGS)
REQUEST FOR SUPPLEMENTAL INFORMATION (RSI) 1-8 Nuclear Regulatory Commission (NRC):10/23/24 and 10/29/24 Jen Whitman (10/23/24 only)
Christepher McKenney Shaun Anderson Amy Snyder Cynthia Barr Kathryn Robertson-DeMers Randy Fedors Kosmos Lois Marlayna Doell Holtec Decommissioning International, Oyster Creek and its Contractors:10/23/24 and 10/29/24 Bill Noval, W.Noval@holtec.com (10/23/24 only)
Steven Johnston, S.Johnston@holtec.com Tom Williamson, t.williamson@holtec.com Kevin Wolf, kg.wolf@holtec.com (10/23/24 only)